EPS Fallback Indication via UE Call Status Signaling

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Solution Overview

Problem

Current communication networks face challenges in efficiently handling Evolved Packet System (EPS) fallback for User Equipment (UE), leading to issues such as incorrect location updates and timer value adjustments during call setups, especially in scenarios involving NG-RAN/NR to E-UTRAN or LTE transitions.

Innovation Solution

The method involves the User Equipment (UE) providing call status information regarding its EPS fallback capability to the Call Session Control Function (CSCF), allowing for improved handling and awareness of EPS fallback capabilities within the network, enabling appropriate adjustments and accurate location updates during call setups.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the UE provides call status information regarding EPS fallback capability to the CSCF, then the network's ability to manage EPS fallback is enhanced and location updates become correct, but the device complexity and signaling overhead increase

Engineering Contradiction:

ImproveEPS fallback management reliabilityVSAvoidsignaling complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The UE provides call status information regarding EPS fallback capability to the CSCF during the call setup phase, before the actual fallback occurs. This preliminary indication allows the network to prepare appropriate handling procedures in advance, ensuring correct location updates and timer value adjustments when EPS fallback is triggered, thereby improving reliability without adding complex runtime decision-making

Inventive Principle:

Principle #10Preliminary action

2Measurement precision

If the network obtains awareness of EPS fallback capability during call setup, then timer values and location updates are improved, but the call setup time and signaling overhead increase

Engineering Contradiction:

Improvelocation update accuracyVSAvoidcall setup time

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The call status information indicating EPS fallback capability is exchanged during the initial call setup signaling between the UE and CSCF, before the actual call connection is established. This allows the network to obtain precise awareness of the UE's fallback capability in advance, enabling accurate location updates and appropriate timer value configurations to be prepared beforehand, thus minimizing any potential time loss during the actual fallback execution

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentEP3864813B1Indication of evolved packet system fallback capability

Publication Date: 2023.12.06 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)

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AI summary

There is provided mechanisms for indicating evolved packet system (EPS) fallback capability. A method is performed by a user equipment (UE). The method comprises providing, towards a call session control function (CSCF), call status information with respect to EPS fallback capability of the UE. There is also provided a UE configured to perform such a method.